Definition
A method of keeping aircraft safely apart by assigning them different altitudes. Air traffic control uses standard vertical spacing values—typically 1,000 feet between aircraft below FL410 and 2,000 feet above—to ensure aircraft on conflicting routes do not collide.
Plain English
Keeping planes safely apart by stacking them at different heights, with set distances between each level.
Context Anchor
You will encounter this in ATC clearances, IFR flying, altitude assignments, and traffic conflict discussions.
Derivation
From Latin verticalis ('overhead, of the highest point') and separare ('to set apart'). Together: keeping things apart in the up-and-down direction.
Why Pilots Care
Maintains safe vertical buffers in busy or crossing traffic; pilots must hold assigned altitudes precisely to avoid violations and mid-air risk.
Grounding Statement
If one aircraft is held at 5,000 feet and another is held at 6,000 feet, they are being kept apart by altitude.
Intuition Check
Vertical separation does not mean general distance from another aircraft. It specifically means separation by height: one aircraft is above or below the other.
Example Sentence 1
ATC maintained vertical separation by holding the inbound traffic at 7,000 feet while we climbed through to 9,000.
Example Sentence 2
In RVSM airspace vertical separation is reduced to 1000 feet between flight levels 290 and 410.